Cutter head for dry shaver

ABSTRACT

TWO LOWER CARRYING RODS ARE SPACED FROM AN UPPER CARRYING ROD ON OPPOSITE SIDES THEREOF. A PLURALITY OF SPACED APART KNIFE BLADES ARE THREADED ON SAID CARRYING RODS. A DRIVER WHICH IS MADE OF PLASTICS MATERIAL COMPRISES A BOTTOM PART WHICH IS FORMED WITH AN APERTURE ADAPTED TO RECEIVE A DRIVE PIN, AND CHEEKS SPACED APART IN THE LONGITUDINAL DIRECTION OF SAID BOTTOM PART AND EXTENDING UPWARDLY FROM SAID BOTTOM PART AND FITTING EACH BETWEEN ADJACENT ONES OF SAID KNIFE BLADES. SAID CHEEKS HAVE OUTER NARROW SIDE FACES FORMED WITH RELIEVED SURFACE PORTIONS IN RESILIENT ENGAGEMENT WITH CONFRONTING PERIPHERAL SURFACE PORTIONS OF SAID LOWER CARRYING RODS.

Feb. 9, 1971 R. ANTRETTER 3,561,118

CUTTER HEAD FOR DRY SHAVER Filed Jan. 17-, 1969 INV'l/TOR 0; MM 9 Z TTURNE l R/chardAnfreHer United States Patent Ofice 3,561,118 Patented Feb. 9, 1971 3,561,118 CUTTER HEAD FOR DRY SHAVER Richard Antretter, 9,Karl Stielerstr., 8031 Stockdorf, near Munich, Germany Filed Jan. 17, 1969, Ser. No. 791,978 Claims priority, application Germany, July 25, 1968, P 17 03 893.6 Int. Cl. B26b 19/06 US. Cl. 30-34651 8 Claims ABSTRACT OF THE DISCLOSURE Two lower carrying rods are spaced from an upper carrying rod on opposite sides thereof. A p urality of spaced apart knife blades are threaded on said carrying rods. A driver which is made of plastics material comprises a bottom part which is formed with an aperture adapted to receive a driver pin, and checks spaced apart in the longitudinal direction of said bottom part and extending upwardly from said bottom part and fitting each between adjacent ones of said knife blades. Said cheeks have outer narrow side faces formed with relieved surface portions in resilient engagement with confronting peripheral surface portions of said lower carrying rods.

The present invention relates to a cutter head for dry shavers, which cutter head comprises an upper carrying rod, two lower carrying rods, which are spaced from said upper rod on opposite sides thereof, spaced apart knife blades threaded on said rods, and a driver, which is made of plastics material and is adapted to receive a driver pin and to be connected to the cutter head by detent seats and comprises a bottom part having an aperture for receiving the driver pin, and spaced apart cheeks which are connected to the bottom part at opposite ends and adapted to be introduced between the knife blades.

Such cutter heads are already known (see, e.g., the printed German application No. 1,246,464). In that known cutter head, the checks of the driver are so long that they extend upwardly beyond the level of the upper carrying rod, and are provided with a central slot, which merges adjacent to the upper carrying rod into a notch, which partly encloses the upper carrying rod. When said driver member is fitted between the knife blades of the cutter head, those side portions of the cheeks which are defined by the central slots are spread apart so that they subsequently engage the lower carrying rods with a clamping action.

Because the clamping force exerted by the outer edges of the checks on the lower carrying rods may not always be sufficient for a firm mounting, the recesses which surround the upper carrying rods must extend upwardly close to the top knife edges of the knife blades.

It is an object of the invention to provide for dry shavers a cutter head which comprises a driver that can be firmly fitted into position and has no parts protruding close to the knife edges of the knife blades. To accomplish that object, it is proposed by the invention to provide a cutter head which is of the kind defined first hereinbefore and in which the cheeks are formed at their outer narrow side faces with relieved surface portions for a resilient engagement with the confronting peripheral sureach cheek into a pair of resilient legs.

The checks are formed with central recess s dividing each cheek into a pair of resilient legs.

In such cutter head, the driver is held on the lower carrying rods by the automatic clamping force exerted by the two legs of one check.

To lock the legs in position, they have a surface portion which conforms to the profile of the carrying rod and which engages the upper portion of the confronting surfaces of the lower carrying rod and preferably by an edge merges into a surface portion which extends toward the free end of the cheek. The transition from that surface portion of the outer end face of the leg which conforms to the profile of the carrying rod to the portion which extends toward the bottom part should preferably be gradual. In a particularly preferred embodiment that surface portion which extends toward the bottom part tangentially adjoins the surface portion which conforms to the profile of the carrying rod and the former portion extends along a straight line at an acute angle to the cheek axis toward the bottom part.

When the driver is pulled out between the carrying rods, this wedge-like taper will increase the clamping force exerted by the legs and this force will have an upwardly directed component tending to draw the driver to its locked position.

In a development of the invention, the bottom part consists substantially of a right-angled frame having a cross-piece which extends parallel to the cheeks and is formed with the aperture for receiving the driver pin, and the bottom part is designed so that the lower edg s of the knife blades rest on the longitudinal members of the frame.

In the driver member according to the invention, the cheeks terminate below the level of the upper carrying rod when the driver is in position. This will ensure that the cheeks do not extend close to the knife edges and a saving in weight will be obtained. This is of great importance in cutter heads because the latter are continually accelerated in operation.

To simplify the fitting of such driver, it is also proposed according to the invention that those knife blades which define the position of the driver have depending extensions.

The above and further features of the invention will now be explained more fully with reference to the drawing, in which an embodiment of the invention is shown diagrammatically and by way of example.

FIG. 1 is a sectional view showing a cutter head according to the invention,

FIG. 2 a perspective view showing the driver according to the invention and FIG. 3 a front elevation showing the driver.

The cutter head consists substantially of the driver 1 and the actual cutting unit 2, which consists of a multiplicity of parallel knife blades 3, which are threaded one behind the other on the lower carrying rods 4 and the upper carrying rod 5. As is best apparent from FIGS. 2 and 3, the bottom part 6 of the driver 1 consists of a rectangular frame which has a cross-piece 7. The latter extends parallel to the checks 9, 10 and contains the aperture 8 for the driver pin 12. This filigree design of the bottom part 6 reduces the mass to be reciprocated and increases the compliance of the cheeks 9, 10.

In order to enable an insertion of the checks 9, 10 between the lower carrying rods 4 when the driver is being fitted into position, each of the cheeks 9, 10 is formed with a wide central recess 10 so that the legs 9 can resiliently yield in an inward direction and their end faces 15, 16 subsequently bear against the lower carrying rods 4 Whereas their surface portions 15 conforming to the profile of the carrying rods 4 snap in between the latter.

As is particularly clearly apparent from FIGS. 1 and 3, those surface portions 16 of the end faces 15, 16 which adjoin the bottom part 6 extend at an acute angle from the vertical so that they have a wedgelike downward taper. At their upper end, there is a smooth transition between these surface portions 16 into those designated 15. The latter surface portions conform to the profile of the lower carrying rods 4. The surface portions 15 merge by edges 17 into surface portions 18 of the legs 9. The surface portions 18 are curved to facilitate their insertion.

In the usual manner, a coil spring 13 surrounds the driver pin 12.

The cutter head according to the invention enables a simple fitting of the driver and ensures that the detachably mounted driver is firmly and immovably connected to the knife unit and will not impair the cutting action of the knives. To ensure a firm and resilient engagement of the surface portions 15 of the legs 9 with the lower carrying rods 4, the width of the checks 9, 10 is selected so that the smallest distance between the surface portions of corresponding legs 9 in relaxed position exceeds the clear distance between the two lower carrying rods 4.

What I claim is:

1. A cutter head for a dry shaver, which comprises an upper carrying rod,

two lower carrying rods spaced from said upper carrying rod on opposite sides thereof,

a plurality of spaced apart knife blades threaded on said carrying rods, and

a driver which is made of plastics material and comprises a bottom part which is formed with an aperture adapted to receive a driver pin, and spaced apart cheeks extending upwardly from said bottom part and fitting each between adjacent ones of said knife blades, said cheeks having outer narrow side faces formed with relieved surface portions in resilient engagement with confronting peripheral surface portions of said lower carrying rods.

2. A cutter head as set forth in claim 1, in which each of said cheeks is formed with a central recess dividing said cheeks into two resilient legs.

3. A cutter head as set forth in claim 1, in which said relieved surface portions conform to said confronting surface portions of said lower carrying rods.

4. A cutter head as set forth in claim 3, in which each of said outer narrow side faces has a free end, a surface portion between said relieved surface portion and said free end, and an edge between the latter surface portion and said relieved surface portion.

5. A cutter head as set forth in claim 3, in which each of said outer narrow side faces has a surface portion which tangentially adjoins said relieved surface portion and extends from the same along a straight line and at an acute angle to the cheek axis toward said bottom part.

6. A cutter head as set forth in claim 1, in which said bottom part comprises a rectangular frame having longitudinal frame members and a cross-piece, which extends parallel to the cheeks and is formed with said aperture, and

said knife blades have lower edges resting on said longitudinal frame members.

7. A cutter head as set forth in claim 1, in which said cheeks have upper ends spaced below the level of said upper carrying rod.

8. A cutter head as set forth in claim 1, in which at least those of said knife blades which engage said cheeks are formed with depending extensions resting on said bottom part.

References Cited UNITED STATES PATENTS 3,332,146 7/1967 Kratz 30-4392 ANDREW R. JUHASZ, Primary Examiner G. F. GRAFEL, Assistant Examiner US. Cl. X.R. 30-43.9l 

